Flushing stylet

ABSTRACT

A stylet includes an elongate body defining a passage and at least one aperture in fluid communication with the passage. The stylet also includes a first blocking dam secured to the elongate body proximal to the at least one aperture and a second blocking dam secured to the elongate body distal to the at least one aperture. The stylet is movable within a lumen of a catheter to a position in which the first and second blocking dams are, respectively, proximal and distal to at least one side opening of the catheter and each of the first and second blocking dams is sealingly engaged with an inner surface of the catheter such that fluid introduced into the lumen, from the passage and through the at least one aperture of the stylet, is directed through the at least one side opening of the catheter.

This application is a divisional of U.S. patent application Ser. No.16/361,638, filed Mar. 22, 2019, and entitled, “Flushing Stylet,” whichis a continuation of U.S. patent application Ser. No. 13/792,411, filedMar. 11, 2013, and entitled, “Flushing Stylet”; the disclosure of eachof the above-identified applications is hereby incorporated by referencein its entirety.

TECHNICAL FIELD

The present disclosure relates to catheters and catheter accessories,and more specifically, to a flushing stylet.

BACKGROUND

Catheters are flexible medical instruments used for withdrawal and/orintroduction of fluids to and from body cavities, ducts, and vessels.Catheters have particular application in hemodialysis procedures, inwhich blood is withdrawn from a blood vessel for treatment andsubsequently returned to the blood vessel for circulation through apatient's body.

Many hemodialysis catheters include multiple lumens, such as dual ortriple-lumen catheters. One lumen is dedicated to withdrawal of fluidfrom a vessel, and at least one other lumen is dedicated to return offluid to the vessel. Generally, the lumen through which fluid iswithdrawn is referred to as the “arterial” lumen, and the lumen throughwhich fluid is returned is referred to as the “venous” lumen. During ahemodialysis procedure, after placement of a multiple lumen catheter ina patient, blood is typically withdrawn from the patient through thearterial lumen of the catheter, and is directed to a hemodialysis unitfor dialysis to remove waste and toxins from the blood. The dialyzedblood is then returned to the patient through the venous lumen of thecatheter.

Generally, hemodialysis catheters are categorized as either acute orchronic. Acute catheters are designed to be placed in a patient underemergent circumstances, under which delays in placement areunacceptable. Acute catheters typically remain in place for only a fewdays. Chronic catheters, by comparison, typically remain in place forextended periods of time, and may be implanted via surgical dissection,which can be performed at the patient's bedside or in an ambulatorysurgical setting.

Catheters, particularly chronic dialysis catheters, may be subject tothrombus formations following placement. These thrombus formations canrestrict or block blood flow through the catheter, potentiallylengthening the time required for treatment, compromising the efficacyof the treatment, and/or requiring more frequent replacement of thecatheter. Methods of dislodging thrombus formations to restore properfluid flow include forcing a solution through the catheter and/or, inthe case of dialysis catheters, reversing the lines of the dialysismachine. Such treatments can be limited by the amount of fluid pressurethat can be built up in the catheter. Moreover, such treatments can havelimited efficacy in catheters with multiple openings, such as catheterswith distal and side openings, because fluids moving through thecatheter tend to bypass those openings with more significant blockagesand exit through those openings that offer less resistance to flow.

SUMMARY

Systems and methods for clearing blockages from catheters are disclosed.In one aspect, a system includes a catheter and a stylet. The catheterincludes a wall having an inner surface and an outer surface, the innersurface defining a lumen, and the wall defining at least one sideopening extending from the outer surface to the inner surface definingthe lumen.

The stylet includes an elongate body and first and second blocking dams.The elongate body defines a passage and at least one aperture in fluidcommunication with the passage. The first blocking dam is secured to theelongate body proximal to the at least one aperture. The second blockingdam is secured to the elongate body distal to the at least one aperture.The stylet is movable within the lumen to a position in which the firstand second blocking dams are, respectively, proximal and distal to theat least one side opening of the catheter and each of the first andsecond blocking dams is sealingly engaged with the inner surface of thecatheter such that fluid introduced into the lumen, from the passage andthrough the at least one aperture of the stylet, is directed through theat least one side opening of the catheter.

In some embodiments, the catheter defines an end orifice distal to theat least one side opening. In certain embodiments, the at least oneaperture of the stylet includes a plurality of apertures axially alignedwith one another, between the first and second blocking dams. In certainembodiments, the at least one aperture includes a plurality of aperturesdisposed about a circumference of the elongate body of the stylet. Insome embodiments, the at least one aperture includes a plurality ofapertures circumferentially and axially offset from each other.

The stylet can include a closed, tapered distal end.

The first and second blocking dams can each include an arcuate outerwall engageable with the inner surface of the lumen. Additionally oralternatively, the first and second blocking dams may include alubricous coating.

In certain embodiments, the stylet includes a marker band disposedbetween the first and second blocking dams and extending around at leasta portion of a circumference of the elongate body. The marker band canbe viewable using one or more imaging techniques including fluoroscopy,magnetic resonance imaging, and x-ray.

In some embodiments, the first and second blocking dams are formed froma material that is more radiopaque than material forming the remainderof the stylet.

In another aspect of the present disclosure, a stylet for use with acatheter includes an elongate body, a first blocking dam, and a secondblocking dam. The elongate body defines a passage and at least oneaperture in fluid communication with the passage. The first blocking damis secured to the elongate body proximal to the at least one aperture.The second blocking dam is secured to the elongate body distal to the atleast one aperture. The elongate body is movable within a lumen of thecatheter to a position in which the first and second blocking dams are,respectively, proximal and distal to a side opening of the catheter andeach of the first and second blocking dams is sealingly engageable withan inner surface of the catheter such that fluid introduced into thelumen of the catheter, from the passage and through the at least oneaperture of the stylet, is directed through the side opening of thecatheter.

The at least one aperture may include a plurality of apertures axiallyaligned with each other between the first and second blocking dams.Additionally or alternatively, the at least one aperture can include aplurality of apertures disposed about a circumference of the elongatebody.

The stylet includes a closed distal end, which may be tapered tofacilitate, for example, passage of the stylet through the lumen of thecatheter.

In some embodiments, the stylet includes a marker band extending aroundat least a portion of a circumference of the elongate body. For example,the marker band can be viewable using one or more imaging techniquesincluding fluoroscopy, magnetic resonance imaging, and x-ray.

In another aspect of the present disclosure, methods are disclosed forincreasing fluid flow through a catheter. The method includes advancinga stylet through a lumen of the catheter, orienting the stylet, andmoving fluid through the stylet. The stylet is oriented such that afirst blocking dam secured to an elongate body of the stylet is distalto a side opening defined by the catheter and a second blocking damsecured to the elongate body of the stylet is positioned proximal to theside opening. The fluid is moved through the stylet and into a spacedefined between the first and second blocking dams to create a zone ofpressure between the elongate body of the stylet and an inner surface ofthe catheter, in fluid communication with the side opening defined inthe catheter to remove a blockage from the side opening.

Orienting the stylet may include forming a seal between an inner surfaceof the lumen of the catheter and each of the first and second blockingdams.

The subject matter of the present disclosure may include one or more ofthe following advantages.

By incorporating first and second blocking dams that form a seal with aninner surface of a lumen defined by a catheter, a zone of pressure canbe created in the axial space between the first and second blocking damssubsequent to the communication of fluid into the stylet. Because theseal formed between the inner surface of the lumen and each of the firstand second blocking dams closes off the remaining portions of the lumen,pressure can be applied to a blockage obstructing the side opening ofthe catheter, regardless of whether the distal opening of the catheteris blocked.

Additionally or alternatively, creating a zone of pressure can reducethe need to align the aperture in the stylet with the side opening inthe catheter, as compared to stylets without first and second blockingdams that may be used to attempt to remove a blockage in a side openingof a catheter.

Moreover, by applying pressure to the blockage through the creation of azone of pressure in the axial space between the first and secondblocking dams, a single aperture may be used, as compared to otherstylets which may generally require multiple apertures to apply fluiddirectly toward the blockage.

Further still, by creating a zone of pressure that is much smaller thanthe entire length of the catheter, less fluid will be needed to providethe pressure necessary to dislodge a blockage. This can, for example,reduce the time necessary to perform the procedure.

Other aspects, features, and advantages of the presently disclosedsubject matter will be apparent from the description, the drawings, andthe claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of a system for use in a medical procedureincluding a catheter and a stylet.

FIG. 2 is an enlargement of the area of detail indicated in FIG. 1 .

FIG. 3 is a transverse, cross-sectional view taken through lines 3-3 inFIG. 1 .

FIG. 4 is a side, perspective view of the stylet of FIG. 1 .

FIG. 5 is a side, plan view of the stylet of FIG. 1 .

FIG. 6 is a longitudinal, cross-sectional view showing the stylet ofFIG. 1 positioned within the catheter of FIG. 1 .

FIG. 7 is a transverse, cross-sectional view taken through lines 7-7 inFIG. 6 .

FIG. 8 is an enlargement of the area of detail indicated in FIG. 6 .

FIG. 9 is a side, perspective view of a stylet.

FIG. 10 is a side, perspective view of a stylet.

FIG. 11 is a side, perspective view of a stylet.

FIG. 12 is a side, perspective view of a stylet.

FIG. 13 is a side, perspective view of a stylet and a catheter.

FIG. 13A is an end view of the catheter seen in FIG. 13 .

FIG. 14A is a transverse, cross-sectional view taken through lines 14-14in FIG. 13 .

FIG. 14B is a transverse, cross-sectional view of a stylet.

FIG. 14C is a transverse, cross-sectional view of a stylet.

FIG. 15 is a longitudinal, cross-sectional view of a stylet positionedwithin the catheter.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the present disclosure will now be described in detailwith reference to the drawings, wherein like reference numerals identifysimilar or identical elements. As used herein, the term “patient” refersto a human patient or other animal, and the term “clinician” refers to adoctor, nurse, support personnel, or other care provider. Additionally,the term “distal” refers to that portion of a device, or a componentthereof, furthest from the clinician during proper use, while the term“proximal” refers to that portion of a device, or a component thereof,closest to the clinician during proper use.

Embodiments of the present disclosure are discussed below in terms ofhemodialysis catheters. However, the principles of the presentdisclosure are applicable to a range of catheter applications includingperitoneal dialysis, surgical, diagnostic, and related treatments ofdiseases and body ailments, such as, for example, the administration andremoval of medication, saline, bodily fluids, and urine. The principlesof the present disclosure are applicable to a variety ofcatheter-related procedures, such as, for example, cardiac, abdominal,urinary, and intestinal procedures, in chronic and acute applications.

Referring now to FIGS. 1 and 2 , a system 10 for use in an exemplarymedical procedure, such as a dialysis procedure, includes a catheter 100and a stylet 200. The catheter 100 defines a side opening 106 and, inuse, the catheter 100 is positioned within a blood vessel V such thatblood can be withdrawn from the blood vessel V and into the catheter 100through the side opening 106. Dialyzed blood can be subsequentlyreturned to the blood vessel V through the side opening 106 or throughanother opening. Over time, particularly over periods associated withchronic catheters, thrombus formation may occur on the outer surface ofthe catheter 100 and/or in the side opening 106, resulting in a blockageB that restricts or occludes blood flow through the catheter 100. Asdescribed in further detail below, a clinician may remove the blockage Bby advancing the stylet 200 through the catheter 100 to the vicinity ofthe side opening 106 and moving pressurized fluid from a fluid source300, through the stylet 200, and toward and through the side opening106. The mechanical force of the pressurized fluid moving through theside opening 106 can dislodge the blockage B from the side opening 106.Additionally or alternatively, chemical activity of the pressurizedfluid (e.g., in the case of heparinized saline) can act to remove theblockage B from the side opening 106. As used herein, the term“blockage” includes any flow restriction inhibiting flow through theside opening 106, such as, for example, thrombus arid/or plaque. Inaddition, for clarity of explanation, a single side opening 106 isshown. However, it should be appreciated that the catheter 100 candefine multiple side openings 106 without departing from the scope ofthe present disclosure. For example, the stylet 200 can be configuredand used to remove blockages B from multiple side openings 106.

Referring now to FIGS. 1-3 , the catheter 100 includes a wall 102 havingan inner surface 110 and an outer surface 105. The wall 102 defines adistal opening 104. The wall 102 also defines a side opening 106extending from the outer surface 105 to the inner surface 110. and theinner surface 110 of the wall 102 defines a lumen 108 that extendslongitudinally through the catheter 100.

The catheter 100 is flexible to facilitate movement of the catheter 100through at least a portion of a patient's vasculature. In someembodiments, the catheter 100 includes a reinforcing material toincrease stability and rigidity. In certain embodiments, the catheter100 includes a pre-curved portion that assumes an arcuate profile in theabsence of any external forces, facilitating conformity of the catheter100 to the configuration of a target tissue, such as the blood vessel Vshown in FIG. 1 , in which the catheter 100 is to be positioned.Alternatively, the catheter 100 may be straight in the absence of anyexternal forces. The catheter may be formed, for example, throughinjection molding and/or extrusion processes.

The lumen 108 extends through the catheter 100 and has a circularcross-section along the length of the catheter. It should beappreciated, however, that the lumen 108 and the catheter 100 may eachassume other configurations without departing from the scope of thepresent disclosure, as will be discussed in further detail below.

Suitable, non-exclusive examples of catheters 100 include thePALINDROME™ and MAHURKAR®. Maxid™ catheters, each of which is madeavailable by Covidien, which maintains a principal place of business at15 Hampshire Street, Mansfield, Mass.

With reference now to FIGS. 4-8 , the stylet 200 is insertable into thelumen 108 extending through the catheter 100, and includes respectiveproximal and distal end portions 202, 204, as well as an elongate body206 defining a passage 210 that extends from the proximal end portion202 to the distal end portion 204.

The proximal end portion 202 of the stylet 200 is connectable to thefluid source 300 (FIG. 1 ). Fluid introduced into the proximal endportion 202, from the fluid source 300, moves through the passage 210extending through the elongate body 206 of the stylet 200. For example,the proximal end portion 202 of the stylet 200 may include a lueradapter 212 connectable to the fluid source 300. The fluid source 300may be, for example, a syringe and/or a pump. The fluid source 300 maydeliver any fluid suitable for facilitating deagglomeration and/ordislodging of the blockage B (FIG. 2 ). Examples of fluid deliverable bythe fluid source 300 to the stylet 200 include saline and ananti-thrombotic fluid, such as heparinized saline.

The distal end portion 204 of the stylet 200 has a closed end 214 anddefines one or more apertures 216. The distal end portion 204 alsoincludes a first blocking dam 218 and a second blocking dam 220. Thefirst blocking dam 218 is proximal to the one or more apertures 216, andthe second blocking dam 220 is distal to the one or more apertures 216.Each blocking dam 218, 220 is sealingly engagable with the inner surface110 of the wall 102 such that the fluid flow is inhibited distallyand/or proximally beyond the first and second blocking structures 218,220. As used herein, the term “blocking dam” refers to a structurespanning the space between the elongate body 206 and the inner surface110 of the wall. For example, a blocking dam can have an inner surfacematching the shape of the elongate body 206 and extends radially fromthe elongate body 206 to an outer dimension OD matching the shape of theinner surface 110 of the wall 102. Specific examples of blocking damsinclude toroids, ovals, and D-shaped structures.

The closed end 214 of the stylet 200 prevents the communication of fluidthrough the distal end portion 204 of the stylet 200, other than throughthe apertures 216. The closed end 214 of the stylet 200 may include atapered portion to facilitate, for example, passage of the stylet 200through the lumen 108 of the catheter 100, and/or passage of the stylet200 distally beyond the distal opening 104 of the catheter 100 to removeblockage from the distal opening 104.

The one or more apertures 216 are defined by the elongate body 206 ofthe stylet 200, and may be positioned adjacent the side opening 106defined by the wall 102 of the catheter 100 via axial movement and/orrotation of the stylet 200 within the catheter 100. The one or moreapertures 216 are in communication with the passage 210 such that fluidcommunicated from the source of fluid 300 (FIG. 1 ) moves through thepassage 210 and exits the stylet 200 through the at least one aperture216.

The first and second blocking dams 218, 220 are secured to an outersurface 222 of the elongate body 206. For example, the first and secondblocking dams 218, 220 can be secured to the outer surface 222 of theelongate body 206 through one or more of monolithic formation, welding,and an adhesive. The first and second blocking dams 218, 220 can beformed from, for example, polyurethane, polypropylene, nylon, syntheticrubber, natural rubber, or any other suitable polymer or elastomericmaterial. The elongate body 206 may be formed from polypropylene,polyethylene, or polyvinyl chloride (PVC).

Each first and second blocking dam 218, 220 defines an outer transversedimension OD that is greater than, or equal to, an inner transversedimension ID defined by the lumen 108 of the catheter 100 such that thefirst and second blocking dams 218, 220 sealingly engage an innersurface 110 of the lumen 108 upon insertion of the stylet 200 into thecatheter 100. In some embodiments, the first and second blocking dams218, 220 are dimensioned such that the outer transverse dimension OD ofeach of the first and second blocking dams 218, 220 exceeds the innertransverse dimension ID of the lumen 108 to an extent sufficient tocause deformation of the wall 102 of the catheter 100 in an outwarddirection, away from a longitudinal axis A defined by the catheter 100.In such embodiments, as the stylet 200 is advanced through the catheter100, the outward deformation of the wall 102 of the catheter caused bythe first and second blocking dams 218, 220 can mechanically disrupt theblockage B (FIG. 2 ), and/or a fibrin sheath associated with thecatheter 100.

The first and second blocking dams 218, 220 may each include an arcuateouter wall 224. As compared to an outer wall with a square profile, suchan arcuate outer wall 224 can, for example, reduce friction associatedwith moving the first and second blocking dams 218, 220 with respect tothe inner surface 110 of the lumen 108, thus reducing the forcenecessary to advance the stylet 200 through the lumen 108 of thecatheter 100. Additionally or alternatively, the blocking structures218, 220 may include a lubricous coating to reduce friction between thefirst and second blocking dams 218, 220 and the inner surface 110 of thelumen 108.

The first and second blocking dams 218, 220 are spaced axially from oneanother by a distance Land can be positioned on opposite sides of theone or more apertures 216. For example, the first blocking dam 218 canbe proximal to the one or more apertures 216, and the second blockingdam 220 can be distal of the one or more apertures 216. The distance Lbetween the first and second blocking dams 218, 220 will depend on thesize of the side opening 106, for example, for the Palindrome™ catheter.In some embodiments, the distance L between the first and secondblocking dams 218, 220 is within the range of 0.5-0.25 inches. However,the longer the distance L, the more leeway a clinician will have toplace the stylet 200 such that the side opening 106 is between the firstand second blocking dams 218, 220.

During use of the stylet 200, fluid communicated from the source offluid 300 (FIG. 1 ) enters the passage 210 of the stylet 200 and exitsthe one or more apertures 216. The seal formed between the first andsecond blocking dams 218, 220 and the inner surface 110 of the catheter100 retains the fluid exiting the one or more apertures 216 within aspace 226 defined between the inner surface 110 of the lumen 108, theouter surface 222 of the stylet, and the first and second blocking dams218, 220. The presence of fluid within the space 226 creates a zone ofpressure isolated from those portions of the lumen 108 outside of thespace 226. The fluid pressure within the space 226 exerts a force uponthe blockage B in a radial direction away from the outer surface 222 ofthe stylet 200 and toward the inner wall 110 of the lumen 108. Thisradially directed force can deagglomerate (e.g., if the stylet 200 isleft in the catheter 100 for a period of time) and/or dislodge theblockage B (FIG. 2 ) from the side opening 106 defined by the wall 102of the catheter 100. It should be appreciated, however, fluid may leakpast the blocking dams 218, 220 because, for example, the fluid pressuremay also cause localized outward deformation of the catheter 100 in thespace 226. Fluid introduced into the space 226 through the stylet 200will still function to remove blockage B even if some of the fluid leakspast the blocking dams 218, 220 and, thus, some leakage is within thescope of the present disclosure.

The elongate body 206 of the stylet 200 has a substantially circularcross-section shape similar to and offset from the shape of the innersurface 110 of the lumen 108 such that the radial spacing between theelongate body 206 and the inner surface 110 is substantially uniformaround the circumference of the pressure zone formed between theelongate body 206 and the inner surface 110 of the lumen. Thissubstantially uniform spacing can facilitate introduction of the stylet200 into the lumen 108 by, for example, reducing the need to orient thestylet 200 with respect to the lumen 108 prior to introduction of thestylet.

Referring now to FIGS. 1-8 , an exemplary method of using the stylet 200includes inserting the stylet 200 into the lumen 108 of the catheter100, which may be positioned within the blood vessel V. As the stylet200 is advanced through the lumen 108 of the catheter 100, the first andsecond blocking dams 218, 220, and in particular, the second blockingdam 220, may act to push any fluid (e.g., lock solution and/or blood)out of the lumen 108 of the catheter 100, potentially contributing todeagglomeration and/or dislodging of the blockage B (FIG. 2 ).

The stylet 200 is advanced through the lumen 108 of the catheter 100toward the side opening 106 including the blockage B (FIG. 2 ), suchthat the second blocking dam 220 is distal to the opening 106 and thefirst blocking dam 218 is proximal to the opening 106, as shown in FIGS.6 and 8 , for example. Because the distance L between the blocking dams218, 220 is greater than the longitudinal dimension of the side opening106, the stylet 200 does not have to be precisely place and, instead,provides some leeway as to final placement of the stylet 200.

The stylet 200 may be advanced through the lumen 108 until the closedend 214 of the stylet 200 extends distally beyond the catheter 100 tomechanically clear any additional blockage such as, for example,thrombus formed at or near the distal opening 104 of the catheter 100.

To facilitate proper positioning of the stylet 200, the stylet 200 mayinclude a marker band 230 viewable using one or more imaging techniquesincluding fluoroscopy, magnetic resonance imaging (M.R.I.), and/orx-ray. The marker band 230 is located between the first and secondblocking dams 218, 220 and extends around at least a portion of thecircumference of the elongate body 206. Although the marker band 230 isshown as being adjacent one of the apertures 216 in FIGS. 6 and 8 , itshould be appreciated that the location of the marker band 230 may bevaried without departing from the scope of the present disclosure. Forexample, the stylet 200 can include one or more marker bands 230 locatedon either or both of the first and second blocking dams 218, 220.Additionally, or alternatively, one or more portions of the stylet 200such as, for example, a portion of the stylet 200 between the first andsecond blocking dams 218, 220, and/or the first and second blocking dams218, 220 themselves, may be formed from a material more radiopaque thanthat comprising the remaining portions of the stylet 200.

With the stylet 200 positioned such that the first and second blockingdams 218, 220 are on opposite sides of the side opening 106, fluid iscommunicated from the source of fluid 300 into the passage 210 of thestylet 200, and through the at least one aperture 216 into the space 226to create the zone of pressure. As the volume of fluid within the space226 is increased, increased pressure is applied to the blockage B untilthe blockage B is successfully dislodged from the side opening 106. Ininstances wherein the side opening 106 is only partially occluded by theblockage B, increasing the volume of fluid communicated into the space226 increases the volume of fluid flowing past the blockage B throughthe side opening 206, further facilitating deagglomeration and/ordislodging of the blockage B.

Using the blocking dams 218, 220 to create the zone of pressure reducesthe need for precise longitudinal and/or circumferential alignment ofthe at least one aperture 216 with the side opening 106.

The stylet 200 can be withdrawn from the lumen 108 (FIGS. 6, 8 ) of thecatheter 100 following, for example, satisfactory dislodging of theblockage B. During withdrawal of the stylet 200, blood may be drawn intothe lumen 108 due, for example, to the sealing engagement of the secondblocking ring 220 with the inner surface 110 of the lumen 108. This canreduce the likelihood of air infiltration into the catheter 100.

With the stylet 200 withdrawn from the catheter 100, the catheter 100may be attached to a dialysis machine (not shown) for a dialysistreatment, and/or may be flushed with a solution and clamped, forexample, during an interdialytic period.

During manufacture, the stylet 200 may be dimensioned for use withstandard length catheters such that the clinician need only advance thestylet 200 as far as it will go into the catheter 100 to place thestylet 200. In such a case, the blocking dams 218, 220 may be closertogether as compared to instances in which the stylet 200 is not placedby advancing the stylet 200 as far as it will go into the catheter 100.In the context of reverse tunnel catheters, however, the length of thecatheter is often determined after a reverse tunneling procedure, andplacement of the catheter. As such, the stylet 200 may be provided witha length longer than the catheter and the at least one aperture 216 maybe advanced until it is approximately adjacent the side opening 106,which can be done under fluoroscopy. Specifically, while the back end ofthe catheter is cut in a reverse tunneling procedure, the distancebetween a distal opening and a side opening 106 is constant in anyspecific catheter. Thus, the clinician need only watch for the distalend 214 of the stylet 200 to extend from the catheter 100, or use markerbands if included on the stylet 200.

While certain embodiments have been described, other embodiments arepossible.

For example, in FIGS. 6 and 8 , the stylet 200 is shown as includingthree apertures 216 in longitudinal alignment with one another, andarranged in a single row. However, because a zone of pressure is used toclear the blockage B from the catheter 100, the apertures 216 may bepresent in greater or fewer numbers, and/or may be configured in otherorientations. For example, as shown in FIG. 9 , a stylet 400 defines asingle aperture 416 only and, as shown in FIG. 10 , a stylet 500 definesmultiple rows of apertures 516 in longitudinal alignment with eachother. Referring to FIG. 11 , a stylet 600 defines a plurality ofapertures 616 in circumferential alignment with each other. As shown inFIG. 12 , a stylet 700 defines a plurality of apertures 716circumferentially and axially offset from one another, for example, in ahelical pattern. As another example, while stylets have been describedas being used in single lumen catheters, other embodiments areadditionally or alternatively possible. For example, with reference toFIGS. 13, 13A, and 14A a stylet 900 can be used with a catheter 1000that defines a first lumen 1002 and a second lumen 1006. The first lumen1002 can be, for example, an arterial lumen, and the second lumen 1006can be, for example, a venous lumen. The first lumen 1002 is in fluidcommunication with a side opening 1004, and the second lumen 1006 is influid communication with another side opening (not shown in FIG. 13 ).The lumens 1002, 1006 of the catheter 1000 are each D-shaped, and areseparated by a septum wall 1010. To facilitate use with the catheter1000, the stylet 900 includes a body 906 that defines a D-shapedcross-section. The stylet 900 may include a first blocking dam 904 and asecond blocking dam 908, which are also both D-shaped, as shown in FIGS.14A-14C, to conform to the lumens 1002, 1006 and retain fluid betweenthe blocking dams 904, 908.

With reference to FIGS. 13 and 14A-14C, the body 906 of the stylet 900may be either partially or fully encircled by the blocking dams 904,908. For example, in FIG. 14A, the body 906 of the stylet 900 is shownas being partially encircled by the blocking dam 908. Alternatively,with reference to FIG. 14B, a stylet 900′ is shown that includes a body906′ that is fully encircled by a blocking dam 908′. The body 906′ ofthe stylet 900′ and the blocking dams, e.g., the blocking dam 908′, mayinclude corresponding configurations, as shown in FIG. 14B.Alternatively, with reference to FIG. 14C, a stylet 900″ is shown thatincludes a body 906″ having a first configuration, e.g., a circularcross-section, and a blocking dam 908″ having a second, differentconfiguration, e.g., a D-shaped cross-section.

While only a single stylet 900 is shown in FIG. 13 , two such styletsmay be employed. For example, one stylet 900 may be used for each of thelumens 1002, 1006 and may be inserted into, and manipulated within, thelumens 1002, 1006 either independently, or simultaneously. As yetanother example, stylets may be dimensioned such that the stylet can beextended distally beyond a catheter to facilitate, for example, removalof a blockage from a distal opening of the catheter while clearing ablockage from a side opening of the catheter. Referring to FIG. 15 , forexample, the distal end portion 204 of the stylet 200 may be dimensionedsuch that the closed end 214 extends distally beyond the catheter 100upon positioning of the side opening(s) 106 within the space 226.

Persons skilled in the art will understand that the devices and methodsspecifically described herein, and shown in the accompanying drawings,constitute non-limiting, exemplary embodiments of the presentdisclosure, and that the elements and features shown or described inconnection with one exemplary embodiment may be combined with those ofanother embodiment without departing from the scope of the presentdisclosure.

As well, one skilled in the art will appreciate further features andadvantages of the presently disclosed stylet based on theabove-described embodiments and the claims. Accordingly, the presentdisclosure is not limited by what has been particularly shown anddescribed.

What is claimed is:
 1. A stylet comprising: an elongate body defining apassage and a plurality of apertures in fluid communication with thepassage; a first blocking dam secured to the elongate body entirelyproximal to the plurality of apertures; and a second blocking damsecured to the elongate body entirely distal to the plurality ofapertures, wherein the first and second blocking dams each defines aD-shaped cross-section, wherein the first and second blocking dams arecircumferentially aligned, and wherein the elongate body is configuredto be movable within a lumen of a catheter to a position in which thefirst and second blocking dams are, respectively, proximal and distal toa side opening of the catheter and each of the first and second blockingdams is sealingly engageable with an inner surface of the catheter suchthat fluid introduced into the lumen of the catheter, from the passageand through the plurality of apertures of the stylet, is directedthrough the side opening of the catheter.
 2. The stylet of claim 1,wherein the plurality of apertures includes apertures axially alignedwith one another along a longitudinal axis of the elongate body.
 3. Thestylet of claim 1, wherein the plurality of apertures includes aperturesdisposed about a circumference of the elongate body.
 4. The stylet ofclaim 1, wherein the plurality of apertures includes aperturescircumferentially and axially offset from each other.
 5. The stylet ofclaim 1, wherein each of the first and second blocking dams includes anarcuate outer wall configured to engage with the inner surface of thecatheter.
 6. The stylet of claim 1, wherein each of the first and secondblocking dams has a lubricous coating.
 7. The stylet of claim 1, whereinthe elongate body includes a closed distal end.
 8. The stylet of claim1, further comprising a marker band extending around at least a portionof a circumference of the elongate body.
 9. The stylet of claim 1,wherein the first and second blocking dams are formed from a materialmore radiopaque than the elongate body.
 10. The stylet of claim 1,wherein the elongate body defines a D-shaped cross-section.
 11. Thestylet of claim 1, wherein the elongate body defines a circularcross-section.
 12. The stylet of claim 1, wherein at least one of thefirst blocking dam or the second blocking dam only partially encirclesan outer perimeter of the elongate body.
 13. The stylet of claim 1,wherein the first blocking dam or the second blocking dam fullyencircles an outer perimeter of the elongate body.
 14. The stylet ofclaim 1, wherein each of the first and second blocking dams is formedfrom polyurethane, polypropylene, nylon, synthetic rubber, or naturalrubber.
 15. The stylet of claim 1, wherein at least one of the firstblocking dam or the second blocking dam is monolithically formed withthe elongate body.
 16. The stylet of claim 1, wherein at least one ofthe first blocking dam or the second blocking dam is welded or adheredto the elongate body.
 17. A system comprising: the stylet of claim 1; afluid source; and the catheter, wherein the elongate body of the styletis configured to fluidically connect to the fluid source and deliver thefluid from the fluid source to the lumen of the catheter via the passageand the plurality of apertures.
 18. A system comprising the catheterdefining the lumen, wherein the lumen is D-shaped; and the stylet ofclaim 1, wherein the first and second blocking dams conform to theD-shaped lumen and are configured to retain fluid between the first andsecond blocking dams when the elongate body and the first and secondblocking dams are inserted in the lumen of the catheter.
 19. A styletcomprising: an elongate body defining a passage and a plurality ofapertures in fluid communication with the passage; a first blocking damsecured to the elongate body entirely proximal to the plurality ofapertures; and a second blocking dam secured to the elongate bodyentirely distal to the plurality of apertures, wherein each of the firstand second blocking dams only partially encircles an outer perimeter ofthe elongate body, wherein the first and second blocking dams arecircumferentially aligned, and wherein the elongate body is configuredto be movable within a lumen of a catheter to a position in which thefirst and second blocking dams are, respectively, proximal and distal toa side opening of the catheter and each of the first and second blockingdams is sealingly engageable with an inner surface of the catheter suchthat fluid introduced into the lumen of the catheter, from the passageand through the plurality of apertures of the stylet, is directedthrough the side opening of the catheter.
 20. A system comprising: acatheter defining a lumen and a side opening, wherein the lumen isD-shaped; and a stylet comprising: an elongate body defining a passageand a plurality of apertures in fluid communication with the passage; afirst blocking dam secured to the elongate body proximal to theplurality of apertures; and a second blocking dam secured to theelongate body distal to the plurality of apertures, wherein the firstand second blocking dams each defines a D-shaped cross-section, whereinthe elongate body is configured to be movable within the lumen of thecatheter to a position in which the first and second blocking dams are,respectively, proximal and distal to the side opening of the catheterand each of the first and second blocking dams is sealingly engageablewith an inner surface of the catheter such that fluid introduced intothe lumen of the catheter, from the passage and through the plurality ofapertures of the stylet, is directed through the side opening of thecatheter, and wherein the first and second blocking dams conform to theD-shaped lumen and are configured to retain fluid between the first andsecond blocking dams when the elongate body and the first and secondblocking dams are inserted in the lumen of the catheter.